. Assessment of Penile Autonomic Innervation The cavernous nerves provide the autonomic innervation of the penis and are crucial to healthy erectile function. However, cavernous neuropathy in humans is not currently tested by any widely accepted method The main objective of this proposal is to investigate cavernous nerve function using electrophysiologic techniques. Our hypothesis is that evoked electrical activity in the corpus cavernosum, known as evoked cavernous activity, is a measure of the integrity of penile innervation by the cavernous nerves. The specific aims in this proposal are: 1. To measure evoked cavernous activity following activation of the sympathetic nervous system in healthy, potent men, and 2. To measure evoked cavernous activity following activation of the sympathetic nervous system in men with erectile dysfunction due to cavernous nerve injury. Cavernous nerve integrity will be determined by recording the electrical activity manifested in the corpus cavernosum using standard clinical electrophysiological equipment modified for use in the male genitalia. The presence of electrical impulses, stimulated by activation of sympathetic fibers, will indicate the integrity of corporal innervation by the cavernous nerves. We will be corroborating measures of erectile function with the electrophysiologic data. These studies are prompted by the significant occurrence of neurogenic erectile dysfunction, particularly n diabetes mellitus and following radical pelvic surgery. In both instances, cavernous nerve disruption is the purported cause for the erectile dysfunction. However, definitive clinical diagnoses are not possible without measure of cavernous nerve function; this will require neurophysiologic methodologies such as EGA. The studies proposed in this application will be the first steps in validating a diagnostic test of cavernous nerve unction. The ability to detect cavernous neuropathy is relevant to the evaluation of erectile dysfunction, as well as the development of disease-specific treatments for neurogenic erectile dysfunction. [unreadable] [unreadable]